n-tier application
lazarus / 16-Databases

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trevisani · 2009-01-18 01:00

Hello list,

I need to create a n-tier application use postgresql and I'm not found
vcl components to do it.
Does anybody knows how to implement this under linux, like
tdatasetprovider, tclientdataset, etc. etc. etc.?

Thanks,

Trevisani.

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Loesje · 2009-01-18 21:39

The basics are in sqldb, but you'll most probably need a very recent
version (2.2.3 or even 2.3.1) of fpc. And you have to do some parts
yourself.

Do you really need a middle-tier layer on a separate machine?

You can use a TSQLQuery on the middle-tier machine, using a normal
'select * from table' connected to the db-server. You can use streams
to connect this data to the end-tier, but you have to implement
something to send this stream through a network yourself. On the end-
tier you can also use a TSQLQuery, but do not open it using a query,
but by assigning a stream (from the middle-tier) to it.

In theory this works, also with updates. But there's a lot that have
to be done to make this all really work...

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trevisani · 2009-01-19 01:58

Thanks Loesje,

I think the 3-tier application is much fast than others ways.
My connection's service is not good (radio wire) and the comunication
is very bad.
Actions like open a query or post are slonly using zeoslib.

I will try yours methods.